5 Modals of Deduction in English: Guide and Examples

The modals of deduction are used to indicate degrees of certainty or probability when making deductions or drawing conclusions about a situation or event.

The English modal verbs “must”, “have to”,”may”, “might” “can’t” and “couldn’t” are used to express deduction and contention.

Modal verbs are used to state how sure the speaker is about something.

These are some examples of how modals can be used to make deductions:

• It’s raining heavily, so they must have canceled the outdoor event.
• He can’t have finished his homework already; he just got home.
• She could be at the library studying for her exams.
• He might have forgotten his wallet at the restaurant
• It may rain later, so don’t forget your umbrella.
• The traffic is terrible; he should be here any minute now.

Now let’s check all that you need to know to make sentences with the modals of deduction correctly

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Modals of Deduction: Must

We use must when we feel sure that something is true because there’s very strong evidence.

1. He must be around here because his car is parked there
2. You are pilot, that must be interesting
3. You have worked all day, you must be tired
4. He has an expensive car, he must have some money
5. He must live near here because he comes to work  on  foot.
6. She’s not here. She must be in the kitchen.
7. You’re a zookeeper? That must be very interesting.
8. Her son is at university so she must be at least 40
9. Carla works every day from 9 AM to 5 PM so she must be at work
10. She isn’t answering the phone, she must be out
11. He drives an expensive car, he must have a good job

We use must have and couldn’t have plus the past participle of the verb to draw a conclusion abouT what happened in the past

• Sheila got a tan. She must have spent a lot of time in the sun lately.

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Modals of Deduction: Might and May

We use might, may or could to say that we think something is possible but we’re not sure.

1. I heard a noise, there might be a cat on the roof
2.  He might be  in his bedroom
3. He might be in the Gym,  sometimes he goes there
4. Jerry is very tall so he might be good at basketball.
5. She is busy, she might not be able to come tonight
6. They might be some kind of small pig.
7. She might be going to Australia.
8. She might have taken those photos in China.

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Modals of Deduction: Can’t

We use can’t when we feel sure something is not true.

1. He can’t be dead, I just talked to him on the phone
2. It can’t be a mechanical problem, the car is new
3. That can’t  be James, James wears glasses
4. My wallet can’t be in my backpack, I already checked there
5. She can’t be a mother, she’s only 14!
6. He can’t be in prison, I saw him yesterday in a pub.
7. They can’t be Spanish, they’re speaking Portuguese
8. That looks like tomato juice, but it can’t be, that would be too easy.

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Modals of Deduction: Could

These are some sentences with the modal could

1. Don’t eat it! It could be poisoned!
2. Don’t put it up there. It could fall off and hit someone.
3. Peter could be at the library.
4. He could be stuck in traffic; that’s why he’s running late.
5. With his qualifications, he could easily get the job
6. The computer is freezing up; it could have a virus
7. The car wouldn’t start this morning; there could be a problem with the battery.

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